E-signatures for tradespeople and builders: sign quotes and contracts on site
Three thousand pounds of extra work, agreed standing in a driveway on a Tuesday. Five weeks later the customer remembers the conversation differently, and all you have is a quote you emailed and the memory of a handshake.
Nobody in the trade signs much. The quote goes out as a PDF, the customer rings and says go ahead, and that is the contract. It works most of the time, because most customers are straight. The losses are concentrated in the few who are not.
And it is a loss, not an inconvenience. A disputed variation is usually a four-figure write-off, and the reason you write it off is almost never that you were in the wrong. It is that you cannot show you were in the right.
Where the money actually goes
- The quote accepted on the phone. You have the PDF you sent. You have nothing showing they accepted it, at that price, before you ordered the materials.
- The variation done on a handshake. They asked for the opening widening while the wall was already open. You priced it there and then and cracked on. It gets queried on the final invoice, eight weeks later, when the goodwill has gone.
- The revision nobody tracked. You sent a quote, then a second one with the kitchen spec changed and £1,400 added. At the end they are quoting figures off the first, and both files are called Quote.pdf.
- The signature you are still chasing. Print it, sign it, scan it, send it back. On a domestic job that is three days of a customer going quiet and starting to shop around. On a commercial one it is three weeks, and your start date drifts.
If you work down the chain there is a fifth: the retention. Practical completion accepted on a date you cannot evidence is a retention release you have no firm ground to chase.
Getting it signed before you leave the drive
Send the quote from the van. The customer gets an email, taps the link, reads it on their phone and signs with a finger. No app to download and no account to create, which matters more than it sounds: the moment a customer has to invent a password, half of them stop. The link stays live for fourteen days, so the ones who want to talk to their other half first still come back to it.
If you want it done while you are stood in the kitchen, open the link on your own phone and hand it across — but know that the certificate then records your device and location, not theirs. On anything that might get contentious, let them open their own email.
What you are holding afterwards
Every signed PDF gets a cryptographic seal — a PAdES B-T signature, the standard set out in ETSI EN 319 142, using RSA-3072 with SHA-256 — and an RFC 3161 timestamp issued by DigiCert. The timestamp does the heavy lifting in an argument about dates: it is worth nothing if the company being asked about the date is also the company issuing it, so ours comes from DigiCert, an independent and publicly trusted authority anyone can check without going near us.
With the sealed PDF comes an evidence certificate: the name and address it went to, when it was opened and signed, the IP and approximate location, the device, and SHA-256 fingerprints of the file before and after sealing. The events are hash-chained, each locking in the one before. Change a character of the history and every seal after it breaks.
The limit of what any of it does, plainly: a signature only proves they agreed to the document in front of them. If your quote says “supply and fit new bathroom” and little else, it proves they agreed to something vague. Spell out what is in and what is not, and the signature is then worth having.
| The question | Emailed quote, verbal go-ahead | Sealed through Pixasign |
|---|---|---|
| Did they accept the price? | You are fairly sure they did | Their signature against that exact figure |
| Which version did they accept? | The last one you sent, probably | A SHA-256 fingerprint of that exact file |
| When did they accept it? | The date on your sent email | A timestamp issued by DigiCert, not by you |
| Who agreed the extra work? | A conversation on site | Name, email, IP, device, to the second |
| Can anyone else confirm it? | They have to take your word for it | Anyone can check the file, free, no account |
Proof that still works when you are not a customer any more
A sealed PDF is an ordinary signed PDF; it opens in normal PDF software and the signature is inspectable there. We also run a free public checker — drop a file in and it tells you whether anything has changed since it was sealed. No login and no account, so a customer, a solicitor or your accountant can check it without ever dealing with us.
Evidence that only works while you keep paying a supplier is not evidence you control. Download your signed quotes and they stand up on their own. The files sit on hardware in Nuremberg with encrypted backups in Reykjavík, nothing in the United States — detail on our security page.
What it costs
Most e-signature tools charge per user, which is a tax on having a team. A two-man firm and a ten-man firm send much the same paperwork per job; only the number of people sending it changes. Per-seat pricing pushes you into sharing one login, and a shared login ruins the one thing you bought it for, because every signature comes back attributed to the same account.
Pixasign is a flat monthly price with unlimited users. £29 a month covers 50 documents, roughly two a working day; £59 covers 200 and £99 covers 500. VAT is included, so the figure you see is the figure that leaves the bank. Put your site managers and the office on it at no extra cost. Your customers never pay and never need an account.
Send your next quote through it
Seven days free, no card. Take the quote you were going to email this afternoon, send it this way instead, and see how fast it comes back signed.
Start free trial UK-built by Pixacomms Ltd, Cardiff. Nothing hosted in the United States.Questions
Is a signature drawn on a phone screen actually binding?
Electronic signatures are valid and enforceable for the vast majority of UK business documents, and a quote, a variation or a contract for building work is ordinary commercial paperwork. A small number of document types carry special formality requirements; if you are unsure whether something you are sending is one of them, ask a solicitor rather than a supplier. What decides a dispute in practice is evidence — who agreed, to which version, and when — and that is the part a sealed document does better than an email thread.
My customers are not technical. Half of them are in their seventies.
They do not need to be. There is no app and no account. They get an email, tap the link, read the quote and sign with a finger or by typing their name. If they get stuck, the link is still live for fourteen days, so you can talk them through it on the phone the following evening.
The customer says they never agreed to that price.
Then you open the sealed PDF and the evidence certificate next to it. It shows the exact file they signed, down to a SHA-256 fingerprint, the name and email address it went to, the IP address and approximate location they signed from, the device, and the time to the second, attested by DigiCert rather than by you. You are no longer arguing about what anybody remembers.
I go quiet over the winter. Do I lose anything if I stop the subscription?
No. Nothing is deleted. The account goes read-only, so every signed quote and contract is still there to open and download, and sending pauses until you start a plan again. Anything you have already downloaded stays valid on its own, because it does not depend on us.